1. Field of the Invention
The present invention relates to a method for producing a material roll for use in a process including bonding an optical film to a surface of an optical display unit.
2. Description of the Related Art
A conventional method for manufacturing a liquid crystal display device includes the steps of producing a roll of an optical film by an optical film maker, then cutting the optical film by the maker into a specific length corresponding to the size of an optical display unit to which the film will be bonded, packaging the specific-length film after appearance inspection, end-face preparation and so on, transporting the packaged film to a panel processing manufacturer, inspecting the appearance of the film by the panel processing manufacturer, and then bonding the film to an optical display unit (such as a liquid crystal panel) after cleaning.
Such a manufacturing process particularly requires the steps of preparing the end face, packaging a piece of the sheet material, and unpacking the material, because the optical film maker and the panel processing manufacturer are located at different places. However, such a multi-step process has the problem of an increase in manufacturing cost. There are also problems in which scratches, dust, stains, and so on can be caused by the multi-step process or the transportation so that an inspection process can be necessary, and problems in which different types of sheet materials must be carried and managed.
Japanese Patent Application Laid-Open (JP-A) No. 2007-140046 discloses a production method to solve the problems. The method includes means for feeding a long sheet material from a roll of the long sheet material including an optical film to be used as a component of an optical display device, means for detecting defects in the long sheet material fed from the feeding means, means for cutting the long sheet material into sheet material pieces based on the result of the detection by the detecting means, means for transporting each sheet material piece cut by the cutting means to a bonding process, and means for bonding the transported sheet material piece to an optical display unit as a component of an optical display device, wherein the respective means are arranged on a continuous production line. The long sheet material including the optical film can be directly cut into the desired size, and the cut piece of the sheet material can be directly bonded to the optical display unit. According to a conventional technique, the long sheet material is stamped into pieces, and the stamped sheet material pieces are each carefully packaged and delivered to a panel processing manufacturer. According to this method, however, a roll of the long sheet material may be directly packaged and delivered.